The prevalence, clinical features, predictive factors and investigations to screen for cancer in patients with inflammatory myositis. A case series from two tertiary care centers in Riyadh, Saudi Arabia.

OBJECTIVES: To describes the epidemiology of cancer in patients with idiopathic inflammatory myopathies (IIM) treated at 2 tertiary centers in Riyadh, Saudi Arabia. METHODS: This was a retrospective multi-center study evaluating the prevalence and the type of malignancy in an IIM population in King Saud University Medical City and King Abdulaziz Medical City between August 2017 to August 2018. RESULTS: In total, 60 patients were included. Four had neoplasms (6.7%), 2 men had lymphoma, a woman had breast cancer and a second, ovarian cancer. Two patients died due to cancer or its complications. Older age (age greater than 40 years), dysphagia, necrotic rash, absence of interstitial lung disease, high erythrocyte sedimentation rate and a negative anti Jo-1 antibody were potentially predictive risk factors for neoplasm. All patients diagnosed with cancer-associated myositis were investigated with routine and invasive modalities. Three of the 4 patients had abnormal findings in both modalities. One patient, the routine investigations were unremarkable, but a computed tomography of the pelvis revealed an ovarian mass that was subsequently diagnosed as malignant.  Conclusion: An individualized approach might be more appropriate for high risk patients. Larger prospective studies are required to confirm the findings of the current study.